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会议名称:

Association of State Dam Safety Officials Annual Conference

召开年:

2016

召开地:

Philadelphia

会议文集:

Association of State Dam Safety Officials annual conference 2016: Association of State Dam Safety Officials annual conference (Dam safety 2016), 11-14 September 2016, Philadelphia, Pennsylvania, USA

主办单位:

Association of State Dam Safety Officials

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  • 题名 作者 来源 发表时间 操作
  • Levee Breach Consequence Model Validated by Case Study in Joso, Japan

    作者:Paul Risher;Cameron Ackerman;Jesse Morrill-Winter;Woodrow Fields;Jason T. Needham; 会议名称:Association of State Dam Safety Officials annual conference 2017年

    In September 2015, extreme rainfall from two tropical cyclones caused the Kinugawa River levee to overtop and breach in three locations near the city of Joso, Japan. Citizens, government agencies, and television news observed the breaches and resultant flood damages. The well-documented disaster provides a unique opportunity to validate levee breach progression, flooding, evacuation, and lifeloss estimations generated by the suite of models used by USACE and others to support levee safety risk assessments. In this paper, we describe how data from social media augmented official sources to create a complete and accurate data set. Specifically, we scoured multiple online sources to describe the breach erosion progression at a level of detail rarely available outside of a controlled environment. We then describe the multi-step modeling process of: 1) setting up the HEC-RAS river hydraulics model, with the required boundary conditions and breach parameters; 2) calibrating the HEC-RAS model to observed breach flow velocities, flood depths, and inundation extents in the leveed area; and 3) using the HEC-RAS results and the available information on warnings and evacuation to validate the estimates of life loss from HEC-LifeSim.

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  • Levee Breach Consequence Model Validated by Case Study in Joso, Japan

    Paul Risher;Cameron Ackerman;Jesse Morrill-Winter;Woodrow Fields;Jason T. Needham;

    Association of State Dam Safety Officials annual conference

    2017年

  • Risk Evaluation of Smaller Levee Systems: A Prototype

    作者:Kayla J. Ranney;Mark E. Baker;Elena Sossenkina;Daniel W. Osmun;Brinton P. Swift; 会议名称:Association of State Dam Safety Officials annual conference 2017年

    The assessment of risk associated with potential modes of levee failure is key to preserving the physical, social, economic, and environmental assets a levee is intended to protect. A levee risk management program should utilize level of detail and analyses representative of the scale of the system and importance of the protected assets. Comprehensive programs have been well established for large critical levee systems; however, a less resource intensive program is acceptable for smaller levee systems. The National Park Service (NPS) has inherited or constructed smaller levee systems where risk of failure is not well understood. Based on their risk-based dam safety program, NPS is prototyping a levee risk management program to evaluate levee conditions and determine action based on risk of levee tailure. The program is being piloted at seven sites. When developing the program, many components typically used to evaluate risk were scaled back. First, a field examination was conducted and documented by a checklist form developed for smaller levee systems. Then, approaches taken for determining loading on levees were adjusted. Hydrologic analysis ranged from simple two-dimensional modeling to review of previous hydrology and hydraulics studies. Once levee conditions were evaluated, a system to qualitatively estimate risk associated with potential modes of levee failure was developed. A risk estimation workshop was conducted with expert elicitation. The results of this effort will allow NPS to take actions at the higher risk levees and inform the development of new NPS levee safety policy and guidelines.

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  • Risk Evaluation of Smaller Levee Systems: A Prototype

    Kayla J. Ranney;Mark E. Baker;Elena Sossenkina;Daniel W. Osmun;Brinton P. Swift;

    Association of State Dam Safety Officials annual conference

    2017年

  • Waiting to Fail: 100 Years of Deferred Attention

    作者:Randall P. Bass;Fares Y. Abdo;Ray E. Martin; 会议名称:Association of State Dam Safety Officials annual conference 2017年

    The Jefferson Lakeside Dam in Richmond, built in about 1895, was a masonry and rubble run of the river dam, built to provide a lake for Lakeside Park. When the Jefferson Lakeside Country Club was created in 1913, the reservoir provided a water source to irrigate the golf course. After years of neglect, repairs were performed in 2003 to stabilize the crumbling dam, which is subjected to frequent high flow events from the 16 square mile (41.4 km~2) highly developed drainage basin. The 2003 repairs were not very successful and the owner decided to abandon the original dam and build a new dam immediately downstream; a roller compacted concrete (RCC) gravity dam was selected. Given the constant overflows and the potential for frequent freeze thaw cycles for this area of Virginia, air entrainment of the RCC considered to be necessary. Given limited funding, an air entrained RCC mix was considered the most appropriate approach to achieve a cost effective design. A very limited number of RCC projects have tried air entrainment so achieving an effective air entrained RCC mixture was going to be critical to the long term performance of the dam. An RCC mixture proportioning study demonstrated that achieving a freeze thaw resistant RCC mix was possible. Other issues related to design and construction included a 36 inch (1 m) main trunk sewer line located under the left end of the dam that had to be protected, few stream diversion options during construction, and limited site staging areas, precluding the use of an onsite RCC plant. The Contractor selected an offsite central ready mix batch plant to mix the RCC and used dump trucks to bring the mixed RCC to the site. Conveyor system delivered the RCC to the placement area. A breakdown at the central mixing plant resulted in a change to a dry batch plant with the mixing and transporting occurring in ready mix trucks. Success was achieved through collaboration between the design team and contractor to identify solutions to quickly overcome obstacles during construction and being able to successfully develop an air entrained RCC mixture even with the different types of ready mix plants utilized.

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  • Waiting to Fail: 100 Years of Deferred Attention

    Randall P. Bass;Fares Y. Abdo;Ray E. Martin;

    Association of State Dam Safety Officials annual conference

    2017年

  • WHAT HAPPENS IF THE DAM BREAKS? AN OWNER'S SUCCESSFUL EAP PROGRAM IN LIGHT OF THE SC FLOODS

    作者:Meghan Caldwell;Hope Walker;Mitch Turner; 会议名称:Association of State Dam Safety Officials annual conference 2017年

    South Carolina's Dam Safety practices and flood protection infrastructure were put to the test in October of 2015. Record breaking rains caused catastrophic flooding, dams failed across the state, and no one anticipated how detrimental the impacts could be. This storm was arguably one of the most prolific rainfall events in recent U.S. history and has since caused many water industry leaders in South Carolina to focus on the efficacy of their dam safety program. One major component of the program is the requirement for high hazard dams to have an Emergency Action Plan (EAP). This paper will include an overview of the process involved with developing SJWD's Emergency Action Plans highlighting the importance of working with multiple state and county agencies and stakeholders to effectively mitigate impacts, improve local and statewide emergency preparedness, and how lessons learned from South Carolina's experience can promote requirements regarding EAP implementation to become more commonplace throughout the country.

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  • WHAT HAPPENS IF THE DAM BREAKS? AN OWNER'S SUCCESSFUL EAP PROGRAM IN LIGHT OF THE SC FLOODS

    Meghan Caldwell;Hope Walker;Mitch Turner;

    Association of State Dam Safety Officials annual conference

    2017年

  • The impact of dam failures on the development of dam safety legislation and policy in the 1970s

    作者:Nathaniel Gee; 会议名称:Association of State Dam Safety Officials annual conference 2017年

    What leads to a dam safety law being passed? Tireless work promoting dam safety and associated public safety impacts, or an actual disaster? The 1970s was perhaps the most significant decade for development of dam safety laws and regulations in the United States. This eventful time is often attributed to the dam failures that occurred in these years, most notably, Buffalo Creek (WV) in 1972, Teton Dam (ID) in 1976, and Kelly Barnes Dam (GA) in 1977. This paper highlights the status of dam safety laws and guidelines at that time and how they were affected by these significant disasters, and also examines the roles of the technical and non-technical communities that worked tirelessly prior to and after the disasters to make significant legislative change.

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  • The impact of dam failures on the development of dam safety legislation and policy in the 1970s

    Nathaniel Gee;

    Association of State Dam Safety Officials annual conference

    2017年

  • Melding Pathways and Mechanisms for Internal Erosion Failure Modes

    作者:John W. France;Jennifer L. Williams; 会议名称:Association of State Dam Safety Officials annual conference 2017年

    Potential failure mode analysis (PFMA) and risk analysis procedures have evolved over the past two decades, particularly for internal erosion failure modes. Initially, internal erosion failure modes were commonly described based on typical pathways - internal erosion through the embankment, internal erosion through the foundation, internal erosion along the outlet conduit, etc. - and often the term "piping" was used interchangeably with internal erosion. More recently, industry guidance documents have tried to re-focus the understanding of internal erosion failure modes according to their processes and mechanisms - backward erosion piping, concentrated leak erosion, contact erosion, and suffusion/suffusion - with "piping" being a subset of internal erosion. Concurrently with this shift in focus to the different internal erosion mechanisms, over the past few years, the FERC and other organizations have required increasing detail in the descriptions of failure modes. This increased detail is needed to fully document the loading condition and mode of failure, from initiation to breach, to confidently categorize the failure mode for a PFMA or estimate nodal probabilities for risk analysis. It has been the authors' experience, from a workshop at the 2016 ASDSO conference and from recent PFMA sessions, that there is confusion among practitioners on how to address pathways and mechanisms in describing internal erosion failure modes. In our opinion, the description needs to include both pathway and mechanism, as the two combined will define how the failure mode initiates and progresses, what considerations should be used to judge its likelihood, and where and how signs of the failure mode may be exhibited at the dam. This paper explains the mechanisms and pathways and how they are combined to fully and accurately describe an internal erosion failure mode.

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  • Melding Pathways and Mechanisms for Internal Erosion Failure Modes

    John W. France;Jennifer L. Williams;

    Association of State Dam Safety Officials annual conference

    2017年

  • Effect of Microbial Induced Calcium Carbonate Precipitation on the Performance of Ponded Coal Ash

    作者:Shahin Safavizadeh;Brina M. Montoya;Mohammed A. Gabr; 会议名称:Association of State Dam Safety Officials annual conference 2017年

    The breach of the Kingston coal ash pond in December 2008 directed many concerns towards the mechanical stability of coal ash impoundments. The loss of shear strength as additional ash was deposited until the coal ash liquefied was the reason for this catastrophic failure. This failure led to contamination of watersheds totaling about 300 acres of the land. The poor mechanical performance of coal ash impoundments has prompted the need to investigate mitigation techniques. Microbial induced calcium carbonate precipitation (MICP) is a novel approach to improve the stability of the coal ash sediments by using natural, biological processes to cement the particles together. The tendency to capture some heavy metals remaining after coal combustion through co-precipitation is another advantage of using MICP treatment. The improvement in mechanical properties is evaluated with a series of laboratory tests and is illustrated through increases in shear stiffness, reduction in compressibility, and increases in undrained shear strength. Traditional incremental load consolidation apparatuses were modified to evaluate the effect of MICP on the compressibility and hydraulic conductivity of coal ash sediment. One-dimensional incremental load consolidation tests were performed after treating the specimens to target shear wave velocities, measured using bender elements. After finishing the incremental loading, the treated specimens were unloaded and reloaded to evaluate the degradation of the calcium carbonate bonds between particles. The effect of treatment and load application on hydraulic conductivity is evaluated by measuring imposed water pressure while injecting deionized water into the specimens. The results reveal that the compressibility of the ash material is reduced, and one-dimensional load cycling indicates that the compressibility remains improved even if the cemented bonds are degraded during the unloading-loading process. Furthermore, the maximum reduction of hydraulic conductivity caused by bio-cementation is one order of magnitude. The undrained shear strength of the treated coal ash was estimated using correlations relating constrained modulus, elastic modulus, and undrained shear strength of the material. The MICP-improved soil properties were used to evaluate the slope stability of the Kingston coal ash pond to demonstrate the potential improvement in system performance. The results indicated that increasing the initial shear wave velocity (V_s) of the coal ash to twice of its initial value using MICP could increase the factor of safety of the slope significantly.

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  • Effect of Microbial Induced Calcium Carbonate Precipitation on the Performance of Ponded Coal Ash

    Shahin Safavizadeh;Brina M. Montoya;Mohammed A. Gabr;

    Association of State Dam Safety Officials annual conference

    2017年

  • Do Yesterday's Earth-Cut Spillway Designs Meet Today's Standards? The Ins and Outs of Earth Spillway Design and Integrity Analysis

    作者:Wesley Hollenbach;Paul Schweiger;Kent R. Finemore;Andy Deichert;Tim Ridley;Jeff McClure; 会议名称:Association of State Dam Safety Officials annual conference 2017年

    The Natural Resources Conservation Service (NRCS), formerly the Soil Conservation Service (SCS), assisted local sponsors in implementing more than 29,000 dams throughout the United States, most of which have an earth-cut auxiliary spillway. An earth-cut auxiliary spillway is a spillway excavated through natural soil and/or rock materials, often protected with vegetation. NRCS designed many of these auxiliary spillways more than 50 years ago using design criteria based upon quasi-empirical methods and engineering judgment, without any formal analysis of their performance during the design storm. Unfortunately, some earth-cut auxiliary spillways did not perform satisfactorily when activated, and a few have completely breached or caused erosion and breaching of the embankment. As dams are being re-assessed and rehabilitated, designers can evaluate the integrity and hydraulic performance of earth-cut auxiliary spillways using new tools developed by the Agricultural Research Service (ARS) and NRCS, such as the SITES and WinDAM B software. To properly apply these tools and understand the results, it is helpful to understand past design criteria and practices as well as the limitations of these new and powerful analytical tools. The purpose of this paper is to present the history and rationale of early earth-cut auxiliary spillway design using examples from the past. This paper describes both good and bad examples of earth-cut auxiliary spillway designs and their performance when activated. The paper also discusses the use of SITES and WinDAM B software for performing screening level assessments using limited data, and comprehensive analyses using detailed subsurface data. The authors share lessons-learned and provide recommendations on how to best use available information, whether it be old or new, to evaluate the performance of earth-cut auxiliary spillways.

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  • Do Yesterday's Earth-Cut Spillway Designs Meet Today's Standards? The Ins and Outs of Earth Spillway Design and Integrity Analysis

    Wesley Hollenbach;Paul Schweiger;Kent R. Finemore;Andy Deichert;Tim Ridley;Jeff McClure;

    Association of State Dam Safety Officials annual conference

    2017年

  • Condition Surveys of Inaccessible Areas of Concrete Dams

    作者:Evan Kopelson;Mike Likavec; 会议名称:Association of State Dam Safety Officials annual conference 2017年

    Starting in 2015, Vertical Access has worked with Puget Sound Energy to perform conditions assessments at two concrete dams. Lower Baker Dam (a gravity-arch dam completed in 1925) and Upper Baker Dam (a gravity dam completed in 1959) are located in Skagit and Whatcom Counties, Washington. As part of the conditions assessment, Vertical Access technicians gained hands-on access to selected areas using industrial rope access techniques. Once in place, technicians documented existing conditions using a direct-to-digital system called TPAS, for Tablet PC Annotation System. Using this system, notable and representative conditions such as cracks and spalls in the concrete were mapped out on elevation views of the dams. Photographs taken of each condition are hyperlinked to the annotated drawing, and automatically renamed with a file name that can be customized for the project. The deliverables provided to Puget Sound Energy include the annotated elevation drawings, photographs and a written report describing the observed conditions. With the condition survey reports provided by Vertical Access, Puget Sound Energy is able to improve surveillance and monitoring of the dams. The annotated drawings and photographs serve as a baseline condition that provides reference for visual observations made during routine inspections. The inability to safely access the downstream face of the arch dam, the spillway chute, and concrete facewall of the gravity dam by other means have limited the quality of information available to identify new concrete defects or document ongoing deterioration. Isolated photographs taken during inspections are often difficult to confidently locate on a large structure because the photographs are focused on the defect. Use of TPAS to directly input visual and numerical survey information on the structure provides the detailed information to be accurately located and effective for monitoring deterioration.

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  • Condition Surveys of Inaccessible Areas of Concrete Dams

    Evan Kopelson;Mike Likavec;

    Association of State Dam Safety Officials annual conference

    2017年

  • Technical Summary of Protections 2016

    作者:Thomas E. Hepler;Brian Crookston;William Fiedler;Miguel A. Toledo; 会议名称:Association of State Dam Safety Officials annual conference 2017年

    The 2nd International Seminar on Dam Protection against Overtopping, or Protections 2016, was held on September 7-9, 2016 at Colorado State University (CSU) in Fort Collins, Colorado. With 48 participants from North America and Europe, Protections 2016 covered a wide range of topics related to physical and numerical modeling of embankment dam overtopping performance, case studies of prototype performance under extreme flood events, and the development of innovative systems for overtopping protection. The identification of potential failure modes and the use of risk to inform overtopping protection decisions was also discussed. The technical program concluded with a discussion of the special characteristics of levees and tailings dams with respect to overtopping. This paper summarizes the highlights of the technical papers presented at CSU, with a brief look back at Protections 2014 held in Madrid, Spain, and future plans for Protections 2018 to be held in the United Kingdom.

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  • Technical Summary of Protections 2016

    Thomas E. Hepler;Brian Crookston;William Fiedler;Miguel A. Toledo;

    Association of State Dam Safety Officials annual conference

    2017年

  • Filter Diaphragm Performance in New Dam and Dam Rehabilitation Projects

    作者:Benjamin C. Doerge; 会议名称:Association of State Dam Safety Officials annual conference 2017年

    Filter diaphragms are used in earth dams to intercept zones of reduced lateral stress due to differential settlement, which can occur along embedded conduits. Natural Resources Conservation Service (NRCS) has published criteria for sizing filter diaphragms, and these have become a widely used standard for designing filter diaphragms for small and medium-sized dams. This paper presents the results of a finite element analysis to check the validity of NRCS filter diaphragm criteria for both new construction and rehabilitation scenarios. The analysis examines the effects of the many factors which can influence the stress conditions in the soil surrounding the conduit. The study generally confirms the safety of the NRCS criteria for typical round and rectangular conduits, but it points to the advisability of performing additional, site-specific analyses under certain circumstances, including larger conduits and those founded on bedrock.

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  • Filter Diaphragm Performance in New Dam and Dam Rehabilitation Projects

    Benjamin C. Doerge;

    Association of State Dam Safety Officials annual conference

    2017年

  • Filter Media Clogging of Small-Slot Drainage Pipes

    作者:Marc T. Miller;Grady Hillhouse; 会议名称:Association of State Dam Safety Officials annual conference 2017年

    Granular internal drains are commonly used for dams and appurtenant structures to relieve piezometric pressure and to control seepage. These drains often include slotted or perforated pipes to collect and convey seepage, and pipe size openings are dependent on the granular filter medium. Clogging of these pipe openings reduces their efficiency and can lead to pressure increases that introduce performance uncertainties and a reduction in dam safety. The industry has trended away from the use of slotted pipes with small openings due to concerns that small slots are prone to clogging when sand is used as the filter medium. Although this concern is widely accepted, published case studies indicate that these findings are generally anecdotal in nature. This paper presents the results of a limited study of sand clogging of small-slot openings. The study considers differing slot sizes under various head conditions, and describes the observed clogging mechanisms.

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  • Filter Media Clogging of Small-Slot Drainage Pipes

    Marc T. Miller;Grady Hillhouse;

    Association of State Dam Safety Officials annual conference

    2017年

  • Evaluating the Spillway Capacity of the Morning Glory Spillway at Harriman Dam

    作者:Damian M. Gomez;Dan Gessler;Justin (Jud) Donaghy; 会议名称:Association of State Dam Safety Officials annual conference 2017年

    Harriman Dam is a 217.5 foot high earthen hydropower dam which was built in 1924 and has since been raised three times. Excess inflows to the dam are discharged through a morning glory spillway with an outside diameter of approximately 160 feet transitioning into a 22.5 foot diameter drop shaft and discharge tunnel. Following recent high flows produced by Hurricane Irene, questions were raised regarding the discharge capacity of the morning glory spillway. Prior to construction, the hydraulic capacity of the spillway design had been evaluated through a theoretical analysis and a series of scale model tests performed at the Alden Hydraulic Laboratory and at a rebuilt crib dam on Sadawga Brook, near the dam site. The scaling and design of morning glory spillways was novel at the time resulting in the 1924 ASCE Journal Article (paper 1551). In the current study, Gomez and Sullivan Engineers performed an updated theoretical analysis of the spillway capacity, including development of a tailwater rating curve for evaluating tailwater impacts on discharge capacity. A detailed three dimensional computation fluid dynamics (CFD) model was also developed by Gomez and Sullivan, for analysis of the spillway capacity, with a peer review performed by Alden Research Laboratory. Analysis of the Harriman spillway revealed a number of unique characteristics of the hydraulic response. The Harriman spillway was found to transition directly from weir control at the crest to full pipe flow, without an orifice condition occurring in the inlet throat. Additionally, the spillway was found to exhibit sub-atmospheric pressures within the drop shaft under high flow conditions, leading to a siphon-like condition in the spillway. This paper will discuss the evolution (1924 to 2017) of the hydraulic analyses of the spillway capacity identifying similarities and differences between the resulting rating curves. One area of focus will be the presence of sub-atmospheric pressures within the drop shaft and the implications on computed capacity. The advantages and disadvantages of physical and computer based models will also be discussed in the context of the study.

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  • Evaluating the Spillway Capacity of the Morning Glory Spillway at Harriman Dam

    Damian M. Gomez;Dan Gessler;Justin (Jud) Donaghy;

    Association of State Dam Safety Officials annual conference

    2017年

  • Steel wire mesh reinforced Geomat for embankment damage protection from rodents and burrowing animals

    作者:Sachin Mandavkar;Paolo Di Pietro;Mehari Weldu; 会议名称:Association of State Dam Safety Officials annual conference 2017年

    The presence of rodents and burrowing animals such as beavers, ground squirrels, and prairie dogs on levees is a historic and ongoing problem that poses a threat to levee integrity. These animals cause damage that increases seepage penetration into the levee causing voids and levee stability issues. Recent studies show an increase in the population of beavers, nutria, and other rodents in central Europe and North America over the last 15 years. In many instances, this leads to serious stability concerns and levee failures along rivers in the floodplain areas. Most of these mammals, however, are protected species. This paper is aimed at illustrating positive experiences in cooperation with universities, research institutes, and environmental agencies regarding measures to permanently safeguard the banks using composite erosion control systems with polymer coated steel wire mesh (as flexible reinforcement component) and geosynthetic (to promote vegetation growth) without harming the animals and their habitats. The steel mesh component works as an effective long-term barrier against the intrusion of mammals. discouraging them from digging inside the core of the levee. An analysis of infested areas led to define the characteristics of these interventions (length, shape, escape ways, population areas, etc.). The study will present several additional benefits of utilizing polymer steel mesh along levees, such as: 1) strong and durable erosion protection in overflow areas, 2) accelerated vegetation growth (increasing stability), 3) surface protection against ice impacts (in northern regions), 4) ease of installation, maintenance, and 5) ability to conform to irregular shapes along the levee slope. This work will present the positive outcome of case studies along the levees in Europe and North America.

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  • Steel wire mesh reinforced Geomat for embankment damage protection from rodents and burrowing animals

    Sachin Mandavkar;Paolo Di Pietro;Mehari Weldu;

    Association of State Dam Safety Officials annual conference

    2017年

  • Risk Assessment of the New Orleans Hurricane Storm Damage Risk Reduction System Complex Closure Structures

    作者:David S. Bowles;David Moore;Robert Turner;Sanjay S. Chauhan; 会议名称:Association of State Dam Safety Officials annual conference 2017年

    The Southeast Louisiana Flood Protection Authority - East (SLFPA-E) is charged with operating and maintaining a major part of the Hurricane Storm Damage Risk Reduction System (HSDRRS) for the Greater New Orleans area. The HSDRRS consists of levees, floodwalls, outfall canals, pump stations and major closures structures, which reduce the risk associated with storm surges. SLFPA-E is developing a risk-informed maintenance program, similar to that used by Rijkswaterstaat in The Netherlands. This paper summarizes some formative aspects of this program for the major closure structures. The process involved facilitated workshops with SLFPA-E and its partners and the complementary use of risk and systems analysis methodologies. The study identified some potential causes of the complex closure structures failing to close on demand that are associated with mechanical and electrical systems, communications, access and human reliability. It also identified some potential risk reduction measures to increase operational reliability.

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  • Risk Assessment of the New Orleans Hurricane Storm Damage Risk Reduction System Complex Closure Structures

    David S. Bowles;David Moore;Robert Turner;Sanjay S. Chauhan;

    Association of State Dam Safety Officials annual conference

    2017年

  • Assessing Watauga Dam for Internal Erosion

    作者:Alan F. Rauch;R. Eric Pease;S. Caleb Douglas;Jim Bryant;Rachel Adams;April Welshans; 会议名称:Association of State Dam Safety Officials annual conference 2017年

    Watauga Dam is a 332-foot tall, rockfill embankment with a compacted clay core. Completed by the Tennessee Valley Authority (TVA) in 1948, the dam is located in a steeply sided, mountain valley in eastern Tennessee. The dam's vulnerabilities to internal erosion failure modes were recently evaluated as part of TVA's ongoing dam safety assurance program. No seepage has been observed, but possible seepage exits are buried beneath the massive rockfill shell of the dam embankment. Potential internal soil erosion mechanisms were systematically cataloged and evaluated using historical design and construction records, numerical seepage models, and data from a network of installed piezometers. The compiled information will be used to support future, quantitative risk assessments of Watauga Dam, as TVA transitions to risk-informed management of dam safety. Lacking a well-defined, standardized analysis approach, this project provides a case study for the assessment of an embankment dam for safety issues related to seepage and internal soil erosion.

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  • Assessing Watauga Dam for Internal Erosion

    Alan F. Rauch;R. Eric Pease;S. Caleb Douglas;Jim Bryant;Rachel Adams;April Welshans;

    Association of State Dam Safety Officials annual conference

    2017年

  • Discovery and Remediation of Deteriorating Timber Trestles within an Embankment

    作者:Bill Kussmann;Dean Steines; 会议名称:Association of State Dam Safety Officials annual conference 2017年

    In October 2010, depressions on the downstream side of the left embankment at the Big Falls Hydroelectric Project were observed that led to the initiation of a Watch Condition of the Emergency Action Plan (EAP). The Federal Energy Regulatory Commission and other stakeholders were notified and a reservoir drawdown was initiated. Following initiation of the EAP, several potential mechanisms for the depressions were hypothesized and evaluated. Potential failure modes, construction records, record drawings, historic photographs and rock/soil conditions were all reviewed. The review of historic photographs indicated that numerous wooden trestles were utilized to transport materials from the bank/shoreline to the project features during the dam's construction in 1922. Drilling investigations were conducted and a repair was completed at twenty-two depression locations; repair consisted of augering into the depressions to remove loose or objectionable material and placing more suitable material.

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  • Discovery and Remediation of Deteriorating Timber Trestles within an Embankment

    Bill Kussmann;Dean Steines;

    Association of State Dam Safety Officials annual conference

    2017年

  • Fort Peck Dam Spillway Modifications -Rock Anchors in Bearpaw Shale

    作者:Elliott E. Drumright;Douglas M. Yadon; 会议名称:Association of State Dam Safety Officials annual conference 2017年

    The nearly one-mile-long (1.6 km) concrete spillway at Fort Peck Dam in northeast Montana was constructed with a cellular concrete terminal (end) structure, but without a formal stilling basin. Periodic use of the spillway, combined with a strong tendency for air slaking of the native Bearpaw Shale bedrock, has eroded the tailrace channel immediately downstream of the terminal structure. Interim repairs were constructed from 2013 through 2016 and included addition of approximately 75-foot-long (22.9 m), slightly inclined anchors to augment connection of the front to back walls of the terminal structure, and vertical anchors to resist unbalanced uplift and hydrodynamic load on a new concrete apron mat constructed immediately downstream of the terminal structure. This paper discusses the unique geotechnical and structural issues that were overcome in the design, construction and testing of the inclined and vertical anchors.

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  • Fort Peck Dam Spillway Modifications -Rock Anchors in Bearpaw Shale

    Elliott E. Drumright;Douglas M. Yadon;

    Association of State Dam Safety Officials annual conference

    2017年

  • Reclamation's Consequence Estimating Methodology - Using a Two-Dimensional Hydraulic Model to Increase Confidence in Fatality Rate Selection.

    作者:Bruce Feinberg; 会议名称:Association of State Dam Safety Officials annual conference 2017年

    Reclamation's consequences estimating methodology (RCEM) uses a flooding intensity parameter to aid in the selection of fatality rates. The flooding intensity parameter, which is the product of depth and velocity (DV), can be obtained from hydraulic modeling results. One-dimensional (1D) hydraulic modeling is often used to produce dam failure inundation data and maps, but the 1D modeling output data does not provide information on lateral variation of DV as distance increases from the river channel. This can be an issue, especially for broad floodplains. Both velocity and depth will vary away from the river channel in locations where population at risk may be situated. Depending on calculation methods, DV derived from 1D modeling of broad floodplains, can both over-or under-estimate the intensity of flooding at populated areas. The use of two- dimensional (2D) hydraulic modeling for dam failure inundation analysis, allows for the calculation of laterally varying depth and velocities within the inundated area. Differences in DV estimates are illustrated through the example of the 1976 failure of Teton Dam. A hydraulic re-creation was completed, based on discharge information, high water marks and aerial imagery. This information is very similar to what would be obtained from a 1D hydraulic model. The DV values obtained from a recent 2D hydraulic model of this flood event are compared to the hydraulic recreation. Results of this comparison serve to illustrate the limitations of 1D dam failure inundation modeling when compared to 2D, the broader range of information which can be obtained from a 2D model, and the corresponding increase in confidence in the selection of fatality rates and the estimation of dam failure life loss for risk analysis.

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  • Reclamation's Consequence Estimating Methodology - Using a Two-Dimensional Hydraulic Model to Increase Confidence in Fatality Rate Selection.

    Bruce Feinberg;

    Association of State Dam Safety Officials annual conference

    2017年

  • The Potential Failure Mode Analysis Does Fit All Sizes - The Foundation for a Successful Dam Safety Management Program

    作者:Frank L. Blackett;Douglas D. Boyer; 会议名称:Association of State Dam Safety Officials annual conference 2017年

    Small dam owners rightfully question whether a commonly accepted dam safety practice equally applies to their project. Sometimes they do and sometimes they do not. A Potential Failure Mode Analysis (PFMA) is one of those concepts that is familiar and widely accepted process within the larger dam safety community, but not always well understood among the smaller owners. Although the concepts are generally well understood among many, its use and application is highly variable across different agencies, owners, and consultants. Large government dam owners who routinely perform robust quantitative dam safety risk analyses clearly understand how to develop a detailed Potential Failure Mode (PFM). Other dam owners sometimes struggle with the usefulness of a PFMA and understanding all of the intricacies associated with developing a detailed PFM that will provide the best insight into the design, performance, and behavior of their dam, and how to apply PFMs to their dam safety program. Conducting a PFMA and developing PFMs is the foundation for providing input to strategic dam safety management activities and actions for inspection programs, surveillance and monitoring activities, emergency action planning, site investigations, engineering studies, risk management, and others, regardless of the size of the dam. Poorly developed, unclear, or confusing, and missing potential failure modes can result in focusing dam safety activities in lower priority areas and/or missing critical dam safety concerns altogether. This paper is intended for any size of dam to provide some insights from lessons learned in conducting and participating in PFMA sessions and reviewing PFMA reports. This paper also addresses some commonly asked questions such as, "how many PFMs do I need for my project, why do I need to separate out all my PFM descriptions, and how do I manage all these PFMs?" Disclaimer: The opinions expressed in this paper are those of the authors and do not represent official guidance or direction from the Federal Energy Regulatory Commission.

    关键字:

  • The Potential Failure Mode Analysis Does Fit All Sizes - The Foundation for a Successful Dam Safety Management Program

    Frank L. Blackett;Douglas D. Boyer;

    Association of State Dam Safety Officials annual conference

    2017年

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